The play begins in front of the terrace at Hunstanton country home. Lady Caroline and a young American girl called Hester discuss the life at country homes. Lady Caroline is concerned with her husband Sir John and constantly tells him what to do. Lady Hunstanton joins in the conversation as well. She announces that Gerald Arbuthnot, her friend's young son, found a great job as a secretary to a gentleman called Lord Illingworth. Lady Stutfield and Mrs. Allonby join the scene as well and the women discuss the purpose of women in society. Lord Illingworth enters the scene while one of the women describes him as a very wicked man. Lord Illingworth joins in the conversation being cynical and humorously ironical. The group discuss British politics, American views and morality.
Lady Hunstanton receives a letter from Lady Arbuthnot informing that she will join them in the evening. Lord Illingworth and Mrs. Allonby discuss life in their mutual cynical way and Mrs. Allonby challenges Lord Illingworth to kiss the young American puritan girl Hester. The two make a way inside for tea and on the way Lord Illingworth notices Lady Arbuthnot's letter and notices that the handwriting is familiar. Mrs. Allonby asks him who it reminds him of and he tells of no one in particular, a woman of no importance.
In the second act Lady Hunstanton, Mrs. Allonby, Lady Stutfield and Lady Caroline discuss the relationship between men and women. Lady Caroline has simple views where married men should listen to their wives and unmarried should be looking for a wife to listen to. Mrs. Allonby has typical, cynical and complicated views. Hester is silently listening in to conversation. After Lady Hunstanton approaches her she angrily comments about their ridiculous views and tells that men and women should equally work together in bettering their lives and equally be punished for their sins.
Lady Arbuthnot enters the scene. In her conversation to Lady Hunstanton about her son Gerard and Lord Illingworth she realizes that Lord Illingworth is someone she knows from her past. She calls for Gerard to talk to him. Gerard insists on Lord Illingworth and his mother to meet and Lord Illingworth recognizes Lady Arbuthnot. When they are left alone Lord Illingworth comments how Gerard is his son. The two discuss their past and how Lord Illingworth broke his promise of marrying her even after she got pregnant. Lord Illingworth insists on being a part of Gerard's life now. Gerard joins them and Lady Arbuthnot insists that he refuses Lord Illingworth's offer. Unable to give a rational reason for it she finally gives in and accepts her son's decision.
At the picture gallery Lord Illingworth and Gerard discuss life and he gives the young man advice on how to be a valuable part of the society. The rest of the guests enter and talk about the meaning of life. Lady Arbuthnot insists of Gerald to take her home. Gerald wants to say goodbye to Lord Illingworth first. Hester joins Lady Arbuthnot and the two talk about punishments for sins and Hester tells Lady Arbuthnot that both men and women and even their children should be punished for their sins. Hester leaves to get Gerard. Gerard enters and is ready to take his mother home and she begs him to leave Lord Illingworth's side and indirectly tells him her story. Hester enters screaming for help and jumping into Gerard's arms, Lord Illingworth insulted her by trying to kiss her. Furious, Gerard starts for Lord Illingworth but Lady Arbuthnot stops him by finally telling him that he is his father.
The final act takes place at Lady Arbuthnot's house. Gerard is writing a letter to Lord Illingworth. Mrs. Allonby and Lady Hunstanton pay Lady Arbuthnot a visit but she is unable to receive them so the two women leave. Lady Arbuthnot joins her son and he reveals to her that he is writing a letter to Lord Illingworth demanding of him to marry her. Lady Arbuthnot is strongly against it and tries to explain to her son how that would be against everything she stands for and everything she endured her whole life. Hester enters the scene taking her side.
Hester confesses to Lady Arbuthnot that she loves her son and wants to marry him. The couple immediately makes plans for their future and go out into the garden for a walk. Lord Illingworth arrives demanding still to be a part of his son's life. Lady Arbuthnot's reveals to him that Gerard would no longer accept him and that the young puritan girl changed his mind. Bitter at this revelation Illingworth calls Lady Arbuthnot his mistress and almost calling Gerard his bastard if Lady Arbuthnot had not stopped him. He finally leaves. The young couple enters and share their happiness with Lady Arbuthnot. Gerard notices Lord Illingworth's glove and asks his mother who it belongs to, who was her visitor. Lady Arbuthnot answers that it was no one in particular, a man of no importance.
